The objective of this new proposal is to use an interactive, collaborative, multidisciplinary approach to train talented young physician-scientists (MD and MD PhD) or PhD scientists for a successful career in investigative hematology research. The rationale for developing this program is our belief that Mount Sinai School of Medicine offers diverse scientific opportunities in an outstanding research environment, that we have a faculty that is dedicated to training scientists and physician-scientists for a career in academic hematology, stem cell biology, and regenerative medicine, and that we wish to have an impact on the education of future investigative hematologists. Faculty have been integrated into this program from various departments and institutes and from the Rockefeller University. Candidates for this training grant will be expected to devote a minimum of two years to training in basic or translational hematology. The trainees will select a mentor from one of the eight broad areas encompassed by this program: normal and malignant hematopoiesis, developmental hematopoiesis, adult and embryonic stem cell research, analysis of signaling pathways in hematologic processes, cell adhesion and migration within hematopoietic tissues and the vasculature, normal coagulation and inherited clotting disorders, immune cell development and function, and cell and gene therapy and transplantation. Throughout the training period, trainees will devote at least 90% of their time to research. Trainees will focus on an individualized research project under the guidance of one or more faculty preceptors. In addition, they will participate in weekly laboratory meetings, spend a portion of their time attending specific divisional, departmental and institutional research-oriented conferences, and will enroll in didactic, graduate level courses during the first and second years of training. Along with the enormous growth in the research portfolio of the Division of Hematology and Medical Oncology and the recruitment of new faculty over the past decade, we are now in a very strong position to provide an exceptional training opportunity that should be a magnet for the many outstanding trainees who wish to pursue a career in academic hematology research in New York City. cRELEVANCE (See instructions): A T32 award is essential for us to develop a training program that is commensurate with the high caliber of our faculty. The proposed training program will expand the pool of well-trained researchers in molecular and cellular hematology by extending the existing research training opportunities at this institution and will help produce some of the future leaders in hematology and stem cell biology research.